Most listings are in the $20's per square foot per year. The Manassas County submarket is going through a a rise in rates. In the last 3 months, the median rate rose $12 per sqft per year. That's a 70% increase in rent.
In the last 90 days, 26 listings have been listed, which means new availabilities most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,410 sqft. Most properties in this region are approximately 2 floors. Most buildings in this market were built in 1989 and are Class B.